1. Field of the Invention
This invention relates to a method and apparatus for feeding slender parts, such as shafts and bolts, to a predetermined place, such as a hole in a steel plate part or a guide hole for s pot welding electrode.
2. Prior Art
In an example of prior art, a chuck mechanism is attached to the front end of a feed shaft connected to a hydraulic cylinder, and the pair of dogs grip a bolt. In this state, the feed shaft is retracted and moved until the bolt reaches an intended place, whereupon the dogs are opened by the action of the chuck mechanism to release the bolt; in this manner, feeding is completed.
In the prior art described above, since the chuck mechanism itself must be provided with a driving device such as an electromagnetic drive or an air cylinder, the chuck mechanism becomes complicated and large-sized. Further, the dogs also become large-sized depending upon the size and shape of slender parts. Therefore, feeding of parts to narrow places becomes difficult. In the method of gripping and feeding a slender part by dogs, even if there is any slight dimensional error in the dogs or there is a foreign substance such as an iron scrap interposed between the dogs and the part, the part holding attitude is undesirably inclined, making it difficult to attain correct feeding.